An "Upgrade" To My Portable Solar Generator, In Some Respects.

A.Justice

Swears he didn't start that fire.
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I had eight 100ah CALB cells, configured for a 12 volt battery (2p4s, 2400 wh), inside a Plano box. It was HEAVY, and bulky, to move around.

I got a deal on some 90ah aluminum EVE cells, and swapped them out. I lost 240 watts, but also lost about half the weight, and gained half my box back, but it's still more than enough for camping trips and emergencies. I can fit the 150 amp JBD BMS in the bottom of the case now, rather than mounted to the wood plate that covers the cells. It's much cleaner looking, and reduces the risk of damage to the BMS.

Thanks for letting me share.
 

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Northernchateau

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The only think I see and question is, connecting it the way you did makes the BMS check a pair of batteries not each cell.
Maybe someone with more experience can chime in about that.
 

MisterSandals

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makes the BMS check a pair of batteries not each cell.
Maybe someone with more experience can chime in about that.
I have been running 2P4S for hundreds of charge cycles with any issues or anything even slightly odd.

I love the simplicity of a single BMS for 8 cells at 12v. I spent some time and effort up front selecting the pairs; i have no way of knowing how much that helped.
 

A.Justice

Swears he didn't start that fire.
Joined
Sep 12, 2020
Messages
840
Location
TN
The only think I see and question is, connecting it the way you did makes the BMS check a pair of batteries not each cell.
Maybe someone with more experience can chime in about that.
It's a pretty common thing to use cells in parallel and series, the BMS monitors each cell "block" of 2 cells. The ones in parallel act as a single cell. I don't think they make BMS's that monitor individual cells that are in parallel.
 

A.Justice

Swears he didn't start that fire.
Joined
Sep 12, 2020
Messages
840
Location
TN
I have been running 2P4S for hundreds of charge cycles with any issues or anything even slightly odd.

I love the simplicity of a single BMS for 8 cells at 12v. I spent some time and effort up front selecting the pairs; i have no way of knowing how much that helped.
I agree, I love 12 volt systems, it makes it so simple to buy accessories at stores and the 4s BMS is easy to use. My only complaint is that I have to use 2/0 wire, and bypass the BMS to run large (over 1500 watts) inverter loads (at least my inverter has a built in LVD). A 24 or 48 volt system would be more efficient to run a big inverter, but I would loose the ability to run all of my 12 volt stuff without a buck converter. It has also saved my ass when I needed to jumpstart my car when nobody else was home.

I got 16 cells and matched the eight I used based on capacity, resting voltage after a full charge, and internal resistance. 9 of them were almost identical, lucky me.

I only bought 8 CALB cells, so I was stuck using all of them, even though they weren't "matched" very well. They still worked with no issues, I just couldn't easily charge to a full 14.4 volts because of cell drift.
 
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